Continuing research on this project is concerned with development of methods which can be used for the synthesis and semi-synthesis of peptides under mild conditions particularly in aqueous solution within "physiological" ranges of pH and temperature. The thiol-labile bridging methods applied earlier to bidirectional solid-phase synthesis of peptides in non-aqueous media will be adapted to solid-phase peptide synthesis on the surfaces of porous glass beads in aqueous and non-aqueous media. The stereoselective enzymatic methods for amino group deprotection which have been explored in a preliminary way will be refined and adapted to solid-phase peptide synthesis in aqueous solution. These developments, in addition to several proposed innovations in the protection of side-chain functional groups are expected to make possilbe the solid-phase synthesis of peptides partially or entirely in aqueous solution within the pH range of 6-8.